Water pump

ABSTRACT

A water pump includes a mechanical seal provided between a housing and a rotary shaft for preventing cooling water from leaking from a whirl chamber. The housing forms a space into which cooling water leaked from between the mechanical seal and the rotary shaft is flown and a water vent for discharging cooling water flown into the space. The housing is joined with a thermostat cover to form a reservoir communicating with the water vent. The reservoir has a drain for releasing evaporated cooling water to the air and a control wall for preventing cooling water remaining as liquid from flowing out through the drain.

TECHNICAL FILED

The present invention relates to a water pump used in cooling an engine,for example.

BACKGROUND ART

Conventionally, a water pump used in a water-cooled engine includes animpellor provided in one end of a rotary shaft supported to a bodythrough a bearing to rotate the impellor for circulating cooling waterthrough the engine. For instance, a water pump disclosed in PatentDocument 1 includes a space defined between a mechanical seal and abearing, in which a few waterdrops entering the space through themechanical seal are discharged to a reservoir provided in a lowerportion of the body through a water vent to allow cooling water to flowout from a drain for establishing communication between the reservoirand the air.

Further, a water pump disclosed in Patent Document 2 includes a grooveprovided in one side of a reservoir for guiding cooling water, a plugprovided in the other side of the reservoir to close the one side of thereservoir, and a drain provided above the plug for establishingcommunication between the reservoir and the air.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: Japanese Unexamined Patent Application    Publication No. 2002-364585-   Patent Document 2: Japanese Unexamined Patent Application    Publication No. 11-336699

SUMMARY OF INVENTION Technical Problem

According to Patent Document 1, the drain is positioned below aconfluence between the water vent and the reservoir, which might causecooling water to flow from the water vent along an inner wall of thereservoir directly into the drain to the outside. Further, since thedrain is provided in a joining portion between a housing and a cover,cooling water might flow along an inner wall of the reservoir bycapillarity into the drain and then to the outside. If cooling waterflows out to the outside, a road surface or parking floor might get wetor an extract from cooling water might be attached to surroundings ofthe drain disadvantageously.

According to Patent Document 2, since cooling water flows out from ajoining portion of the plug along an inner wall of the reservoir bycapillarity to the outside through the drain, a road surface or parkingfloor might get wet or an extract from cooling water might be attachedto surroundings of the drain disadvantageously. In addition, use of plugmight result in increase in the number of parts and the number orprocess steps, which disadvantageously raises the overall costs.

The present invention has been made having regard to the abovedisadvantages, and its object is to provide a water pump for preventingcooling water from flowing out to the outside to wet a road surface orparking floor, preventing an extract from cooling water from beingattached to surroundings of a drain, and further reducing both of thenumber of parts and the number of process steps to lower the overallcosts.

Solution to Problem

A first solution according to the present invention is in a water pumpcomprising a housing; a cover joined with the housing; a rotary shaftformed in joined surfaces of the housing and the cover and projecting toa whirl chamber; an impellor synchronized with the rotary shaft torotate in the whirl chamber; and a mechanical seal provided between thehousing and the rotary shaft for preventing cooling water from leakingfrom the whirl chamber, in which the housing forms a first space intowhich cooling water leaked from the mechanical seal is flown and a watervent for discharging cooling water flown into the first space, thehousing is joined to the cover to form a second space communicating withthe water vent in at least one of the housing and the cover, and thesecond space has a drain for releasing evaporated cooling water to theair and a control wall provided in at least one of the housing and thecover for preventing cooling water remaining as liquid from flowing outthrough the drain.

A second solution according to the present invention lies in that thesecond space is divided into two chambers by the control wall, one ofwhich is configured to reserve cooling water flowing in from the watervent, the other of which communicates with the drain, the two chamberscommunicating with each other.

A third solution according to the present invention lies in that thesecond space is divided into a chamber and the drain, the chamber andthe drain communicating with each other.

A fourth solution according to the present invention lies in that thedrain is positioned at a level in the direction of gravity between aconfluence of the first space and the water vent and a confluence of thewater vent and the second space.

A fifth solution according to the present invention lies in that thedrain is smaller than the water vent.

Advantages Effects of Invention

According to the first solution, the control wall provided in the secondspace prevents cooling water from flowing directly into the drain due toacceleration in all directions during travel of a vehicle or vibrationsfrom an engine, restrains cooling water from flowing out to the outsideto wet the road surface or parking floor, and restrains the extract fromcooling water from attaching to the surrounds of the drain. In addition,since the housing is joined to the cover to form the second space, adrain plug is dispensable to reduce both the number of parts and thenumber of process steps to lower the overall costs.

According to the second solution, since the second space is divided intotwo chambers by the control wall, cooling water is prevented fromflowing along a wall of the second space into the drain, and evaporatedcooling water can be released from the drain to the air.

According to the third solution, since the second space is divided intothe chamber and the drain by the control wall, cooling water isprevented from flowing along the wall of the second space into thedrain, and evaporated cooling water can be released from the drain tothe air.

According to the fourth solution, since the drain is positioned at thelevel in the direction of gravity between the confluence of the firstspace and the water vent and the confluence of the water vent and thesecond space, cooling water flown into the second space from the watervent is prevented from flowing from the water vent along the wall of thesecond space into the drain.

According to the fifth solution, evaporated cooling water can bepositively discharged to the outside through the drain. Further, thedrain is formed to be smaller than the water vent, which effectivelyrestrains liquid cooling water from flowing out to the outside.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view of a water pump according to a first embodimentof the present invention;

FIG. 2 is a sectional view of the water pump taken on line II-II in FIG.1 according to the first embodiment of the present invention;

FIG. 3 shows a housing as viewed from a side of a whirl chamberaccording to the first embodiment of the present invention;

FIG. 4 shows a thermostat cover as viewed from the side of the whirlchamber according to the first embodiment of the present invention;

FIG. 5 is a sectional view of the water pump taken on line V-V in FIG. 1according to the first embodiment of the present invention; and

FIG. 6 is a sectional view of the water pump according to a secondembodiment of the present invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

FIG. 1 is a front view of a water pump 1 including a metal housing 2molded by forging, for example, a thermostat cover (cover) 3 joined withthe housing 2 through a bolt with an unillustrated gasket being heldtherebetween, and a pulley 5 fixedly bolted to one end of a rotary shaft4.

FIG. 2 is a sectional view of the water pump 1 taken on line II-II ofFIG. 1. The water pump 1 includes the housing 2, the thermostat cover 3joined with the housing 2, a whirl chamber 6 formed in joined surfacesbetween the housing 2 and the thermostat cover 3, the rotary shaft 4projecting from the housing 2 to the whirl chamber 6, an impellor 7press fitted to a distal end of the rotary shaft 4 to be synchronizedwith the rotary shaft 4 to rotate, and a mechanical seal 8 providedbetween the housing 2 and the rotary shaft 4 for preventing leakage ofcooling water from the whirl chamber 6.

Within the housing 2 are formed a space (first space) 9 into which asmall amount of cooling water leaked from the mechanical seal 8 flows, avapor vent 10 for discharging gaseous cooling water having flown intothe space 9, and a water vent 11 for discharging liquid cooling waterhaving flown into the space 9. The water vent 11 communicates with areservoir (second space) 12 formed in the joined surfaces between thehousing 2 and the thermostat cover 3 in the side of the housing 2.

FIG. 3 shows the housing 2 viewed from the whirl chamber 6. Thereservoir 12 is divided into two chambers communicated with each otherthrough a control wall 14 provided in a horizontal direction withrespect to the gravity. One of the chambers is a chamber 12A formed in alower portion of the control wall 14 in the direction of gravity, andthe other is a chamber 12B formed in an upper portion of the controlwall 14 in the direction of gravity. The chamber 12A has a confluencewith the water vent 11 and has an area larger than that of the chamber12B.

FIG. 4 shows the thermostat cover 3 viewed from the whirl chamber 6. Thereservoir 12 is divided into the two chambers communicated with eachother through the control wall 14 provided in the horizontal direction.One of the chambers is the chamber 12A formed in the lower portion ofthe control wall 14 in the direction of gravity, and the other is thechamber 12B formed in the upper portion of the control wall 14 in thedirection of gravity. The chamber 12B communicates with a drain 13 andthe area of the chamber 12A is larger than that of the chamber 12B.

The drain 13 is provided below the control wall 14 from the confluencebetween the space 9 and the water vent 11 and above the control wall 14from the confluence between the water vent 11 and the reservoir 12 withrespect to the direction of gravity. The drain 13 is smaller than thewater vent 11.

FIG. 5 is a sectional view of the water pump 1 in the first embodimenttaken on line V-V of FIG. 1. The control wall 14 projects from both ofthe housing 2 and the thermostat cover 3 to define a small communicatingportion 15 relative to the control wall 14 adjacent to the joinedsurfaces. The communicating portion 15 allows the chamber 12A and thechamber 12B to communicate with each other. The chamber 12A has a volumelarger than that of the chamber 12B.

The operation and effect of the water pump 1 in the first embodimentwill be described hereinafter. The rotary shaft 4 is rotated by anunillustrated belt wound around the pulley 5. A sprocket instead of thepulley 5 may be configured to rotate the rotary shaft 4 by a chain. Whenthe rotary shaft 4 is rotated, the impellor 7 is synchronized with therotary shaft 4 to rotate in the whirl chamber 6, and cooling water issupplied from the water pump 1 to each part of the engine through awater jacket. In this time, a small amount of cooling water is flowninto the space 9 through the mechanical seal 8, and vaporous or steamycooling water is discharged through the vapor vent 10 from the space 9while liquid cooling water is flown into the water vent 11 and guided tothe reservoir 12.

Cooling water is flown into and reserved in the chamber 12A provided inthe lower part of the reservoir 12 divided into the two chambers in thedirection of gravity. Cooling water reserved in the chamber 12A flowsalong a wall surface of the chamber 12A toward the chamber 12B due toacceleration in all directions during travel of a vehicle and vibrationsfrom the engine, but returned to the chamber 12A by the control wall 14(acting as what is called a rat guard), which prevents cooling waterremaining as liquid from flowing out from the drain 13. Cooling waterthat has been evaporated again in the chamber 12A flows into the chamber12B through the communicating portion and is released to the air throughthe drain 13.

Therefore, a road surface or a parking floor is prevented from gettingwet with cooling water, or an extract from cooling water is preventedfrom being attached to surroundings of the drain.

Further, since the reservoir 12 is formed by joining the housing 2 andthe thermostat cover 3, a drain plug is dispensable. Thus, both thenumber of parts and the number of process steps can be reduced to lowerthe overall costs.

Second Embodiment

FIG. 6 is a sectional view of a water pump in a second embodiment. Thelike reference signs used in the first embodiment are assigned to likeparts and like arrangements in the second embodiment. A reservoir 12C isdivided into a chamber 12D and a drain 13A by a control wall 14A, and isformed by a chamber 12D extending in a horizontal direction with respectto the gravity and a chamber 12E extending perpendicularly to thechamber 12D to form a general inversed T shape. The chamber 12D has aconfluence with the water vent 11, the chamber 12E communicates with thedrain 13, and the chamber 12D has a volume larger than that of thechamber 12E. In other words, the chamber 12D is provided in one side ofthe control wall 14 (in the side of the direction of gravity) while thedrain 13 is provided in the other side of the control wall 14 (in theside of the upper direction). The chamber 12E is provided in a distalend side of the control wall 14A (opposite side of the drain 13A openedto the outside).

The operation and effect of the water pump in the second embodiment willbe described hereinafter. The rotary shaft 4 is rotated by anunillustrated belt wound around the pulley 5. A sprocket instead of thepulley 5 may be configured to rotate the rotary shaft 4 by a chain. Whenthe rotary shaft 4 is rotated, the impellor 7 is synchronized with therotary shaft 4 to rotate in the whirl chamber 6, and cooling water issupplied from the water pump 1 to each part of the engine through awater jacket. In this time, a small amount of evaporated cooling wateris flown into the space 9 through the mechanical seal 8, and vaporous orsteamy cooling water is discharged through the vapor vent 10 from thespace 9 while liquid cooling water is flown into the water vent 11 andguided to the reservoir 12.

Cooling water is flown into and reserved in the chamber 12D provided inthe lower part of the reservoir 12C having a general inversed T shape inthe direction of gravity. Cooling water reserved in the chamber 12Dflows along a wall surface of the chamber 12D toward the chamber 12E dueto acceleration in all directions during travel of a vehicle andvibrations from the engine, but returned to the chamber 12D by thecontrol wall 14 (acting as what is called a rat guard), which preventscooling water remaining as liquid from flowing out from the drain 13A.Cooling water that is evaporated again in the chamber 12D flows into thechamber 12E through the communicating portion and is released to the airthrough the drain 13A. Therefore, the road surface or parking floor isprevented from getting wet with cooling water, or the extract fromcooling water is prevented from being attached to the surroundings ofthe drain.

Further, since the reservoir 12 is formed by joining the housing 2 andthe thermostat cover 3, a drain plug is dispensable. Thus, both thenumber of parts and the number of process steps can be reduced to lowerthe overall costs.

Instead of the thermostat cover 3, any other member such as a timingchain cover or a cylinder block may be joined to the housing 2. Also, adrive source for the water pump 1 may be a motor.

It should be noted that the description “cooling water leaked from themechanical seal 8” includes not only the situation in which coolingwater is leaked from the mechanical seal 8 per se but also the situationin which cooling water is leaked from sliding surfaces between therotary shaft 4 and the mechanical seal 8.

DESCRIPTION OF REFERENCE SIGNS

-   1 water pump-   2 housing-   3 thermostat cover (cover)-   4 rotary shaft-   5 pulley-   6 whirl chamber-   7 impellor-   8 mechanical seal-   9 space (first space)-   10 vapor vent-   11 water vent-   12 reservoir (second space)-   12A chamber A-   12B chamber B-   12C reservoir C (second space)-   12D chamber D-   12E chamber E-   13 drain-   13A drain A-   14 control wall-   14A control wall A-   15 communicating portion

1. A water pump comprising: a housing; a cover joined with the housing;a rotary shaft formed in joined surfaces of the housing and the coverand projecting to a whirl chamber; an impellor synchronized with therotary shaft to rotate in the whirl chamber; and a mechanical sealprovided between the housing and the rotary shaft for preventing coolingwater from leaking from the whirl chamber, wherein the housing forms afirst space into which cooling water leaked from the mechanical seal isflown and a water vent for discharging cooling water flown into thefirst space, wherein the housing is joined to the cover to form a secondspace communicating with the water vent in at least one of the housingand the cover, and wherein the second space has a drain for releasingevaporated cooling water to the air and a control wall provided in atleast one of the housing and the cover for preventing cooling waterremaining as liquid from flowing out through the drain.
 2. The waterpump as defined in claim 1, wherein the second space is divided into twochambers by the control wall, one of which is configured to reservecooling water flowing in from the water vent, the other of whichcommunicates with the drain, the two chambers communicating with eachother.
 3. The water pump as defined in claim 1, wherein the second spaceis divided into a chamber and the drain, the chamber and the draincommunicating with each other.
 4. The water pump as defined in claim 1,wherein the drain is positioned at a level in the direction of gravitybetween a confluence of the first space and the water vent and aconfluence of the water vent and the second space.
 5. The water pump asdefined in claim 1, wherein the drain is smaller than the water vent.